1. Field of the Invention
The disclosure relates to a sniffing leak detector comprising a sniffing probe which, via a first suction line leading to a test gas sensor, is connected to a main device including a vacuum pump device.
2. Discussion of the Background Art
Normally, in leak testing of containers and pipe systems, helium is used as a test gas, and the leakage of helium is detected with the aid of a mass spectrometer or another test gas sensor.
DE 10 2005 021 909 A1 (INFICON) describes a sniffing leak detector comprising a sniffing probe to be guided by hand so as to examine a test object for leaks from which test gas is escaping. Via a flexible sniffing line, said sniffing probe is connected to a main device which includes the test gas sensor and the required vacuum pump device.
DE 10 2005 009 713 A1 (INFICON) describes a leak detector comprising a sniffing probe, wherein the sniffing probe is connected to the main device via a hose line including at least two capillary lines. With the aid of valves, said capillary lines can be shut off individually or in groups. By selecting a desired number of capillary lines, the magnitude of the conveying gas flow sucked into the sniffing probe can be changed. Thus, it is possible to select the flow into the sniffing probe to be large so that the response time will be reduced to a minimum and, nonetheless, a sufficient quantity of air will be taken up by the sniffing probe even from a larger distance. The smallest verifiable leakage rate corresponds to the smallest detectable test gas concentration. Thus, the smallest verifiable leakage rate will worsen with increased gas flow into the sniffing probe. By using a plurality of capillaries, it is achieved that a suitable gas flow can be selected for a given application without the need to change the hose line. The concentration of the test gas in the sucked-in gas flow is a measure for the leakage rate. For precise determination of the leakage rate, it is required that, during the measurement, the gas flowing out of a leak will be sucked in completely. The larger the sucked-in conveying gas flow is, the higher the distance sensitivity will be. The term “distance sensitivity” is to be understood as the ability of performing a leak detection at a larger distance from the test object. The sensitivity stands in contrast thereto. The sensitivity will be all the higher, the smaller the leakage rate is that can just about be detected. Two difficulties have to be eliminated. The provision of a large gas flow passing through the suction line will result in increased demands to the line and pump system. On the other hand, there have to be guaranteed a high distance sensitivity and a high sensitivity.
It is an object of the disclosure to provide a sniffing leak detector which fulfils the above demands and is able to search for leaks by use of a high gas throughput and thus to find a leak with high distance sensitivity and, finally, to quantitatively determine the leak with high accuracy by use of a reduced flow.